The invention relates to a pump arrangement, in particular a magnetic clutch pump arrangement.
The pump arrangement has an interior space formed by a pump casing, a containment can which hermetically seals off a chamber surrounded by said containment can with respect to the interior space formed by the pump casing, an impeller shaft which is mounted by way of a plain bearing arrangement and which can be driven in rotation about an axis of rotation, having an impeller arranged on one end of the impeller shaft, a first bearing sleeve connected non-rotationally to the impeller shaft, a second bearing sleeve connected non-rotationally to the impeller shaft, a first bearing bushing which interacts by way of a radial bearing surface with the first bearing sleeve and which is connected non-rotationally to the pump casing or to a component fastened to the pump casing, a second bearing bushing which interacts by way of a radial bearing surface with the second bearing sleeve and which is connected non-rotationally to the pump casing or to a component fastened to the pump casing, and a retaining ring arranged between the first and second bearing bushings.
European patent document no. EP 0 771 956 A1 has disclosed a magnetic clutch pump of said type with a plain bearing arrangement, in the case of which the static bearing parts are received in a bearing ring carrier, referred to as outer casing, and the bearing parts which rotate about the axis of rotation are positioned on the shaft. Here, the axial bearings are each assigned a static bearing part from the outside. This has the disadvantage that the impeller and the bearing bushing arranged closest to the impeller are spaced apart to a relatively great extent, and thus there is a relatively large spacing between said bearing bushing and the radial force that arises at the impeller. Furthermore, an exchange of the static bearing parts is possible only with great outlay and using special tools.
It is the object of the invention to further develop a generic pump arrangement such that the lubrication of the axial bearing is further improved, the radial bearing forces under given loads are reduced, and ease of servicing is increased.
The object of the invention is achieved in that a first ring groove, which receives a first axial bearing ring, is formed in the retaining ring on the face side facing toward the first bearing bushing, and a second ring groove, which receives a second axial bearing ring, is formed in the retaining ring on the face side facing toward the second bearing bushing.
Owing to the positioning of the axial bearing rings between the first and second bearing bushings, the lubrication and cooling of the axial bearing arrangements thus formed is optimized in relation to the prior art. Likewise, the two axial bearing arrangements are thus situated at a position with the least shaft bending, whereby axial bearing tilting is reduced in relation to the prior art, and the contact ratio is increased.
In an advantageous refinement, the first bearing sleeve and the first bearing bushing are arranged in an opening of the casing cover.
In this way, it is possible for the first bearing sleeve and first bearing bushing to be positioned closer to the impeller, whereby the radial forces in the bearing can be reduced, and a lower likelihood of bearing failure at operating points that are critical with regard to radial thrust is realized.
To achieve secure seating of the axial bearing rings, it is provided, in a preferred refinement of the invention, that the first axial bearing ring is clamped in the first ring groove by way of an undular washer, and the second axial bearing ring is clamped in the second ring groove by way of an undular washer.
In a preferred refinement of the invention, for optimum lubrication and cooling of the plain bearing arrangement, it is provided that, in the retaining ring, there is formed at least one bore which connects the first ring groove to a further ring groove formed in the retaining ring in a region facing toward the impeller shaft.
For the same reason, according to the invention, in the retaining ring, there is formed at least one bore which connects the second ring groove to the ring groove formed in the retaining ring in the region facing toward the impeller shaft.
For simple and inexpensive assembly, in an advantageous refinement of the invention, an opening in a casing cover of the pump casing has an opening region of increased diameter, in which opening region there is formed an encircling groove which receives a tolerance ring, and in which opening region the first bearing bushing is positioned and connected non-rotationally to the casing cover by way of the tolerance ring.
Furthermore, it is expediently the case that an opening in the bearing ring carrier has an opening region of increased diameter, in which opening region there is formed an encircling groove which receives a tolerance ring, and in which opening region the second bearing bushing is accommodated and connected non-rotationally to the bearing ring carrier by way of the tolerance ring.
An arrangement of the first bearing bushing in the casing cover and of the second bearing bushing in the bearing ring carrier has the advantage that the plain bearing arrangement or parts thereof can be exchanged in an easy manner with regard to servicing, without the use of special tools.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.